Circulation electrolyzer for alkaline chlorides



F. GRDANK ET AL.

CIRCULATION ELECTROLYZER FOR ALKALINE CHLORIDES Filed Oct. 18, 1922 @as cimas/bev? Y?. in.

remesa oci. zo, 1925.

UNITED STATES PAT l ists-,ess ENT orties.D

FRANCESCO GIGRDANI AND UMBERTO POMILIO, F NAPLES, ITALY.

CIRCULATION ELECTROLYZER FOB. ALKALINE UHLQRDS.

Application filed ctober 1S, 1922. Serial No. 595,220.

T0 al iv/iom it 'may concern.'

Be it known that I, FnANCEsCo GronDANI, a subject of the Kingof' ltaly, residing at Naples, in the Kingdom of Italy, and I Uiminaro Pomme, a subject of the King ol: italy, residii'lgr at Naples, in the Kingdom of Italy, have invented certain new and useful Improvements in1Circulation Electrolyzers for Alkaline yChlo'rides, of which the following is a specification.

The efficiency/of diaphragm electrolyzers ior alkali chlorides' isliinitedby the migration of the ions OH in th'e anodic section, a migration which becomes the more conspicuous the higher is thefconcentration of the alkali inthe cathodic section.

ln order to obtain a high eiiiciency while working Withnottoo'loiv concentrations it1 has already been proposed to cause a general movement of the liquid 4through the `tiliaphragm en -the anode towards the cathode,l so as to` reduce'the:` speed of the said ions measured in respect o' the separating diaphragm.

.However when trying to practice this suggestion, which aimsat eilecting a filtration acrossthe diaphragm, it has generally been lost sight of the fact that the porosity of the diapln'agin itself cannot he increased beyond a certa/in value without the phenomena of physical, "diffusion assuming a consider-` able importance. Hence the necessity to ob-`y tain the circulation of the liquid through a i -nottoo small hydrostatic pressure.

lf then thefaet is taken into considera- 't'ion vthat,,-dming the operation the physical characteristics of thewdiaphragm generally arealtered inthe direction of a diminution Vof its porosity, andA there'foreyof its per`F nieability, it may be seen how it is neces lsery to providev in a continuous and con.

trollable way for the Vvariation of the adiustment.

heights of the anodic liquid to be filtered.

@n the other hand ythe speed ofthe efiiux ought tobe'equal vinievery part of the diaphragm in ordento always. keep it inthe best; Working conditions. To4 this would iny deed answer an apparatus with horizontal' diaphragme, liii a. very high anodic chamber could be provided, so as to enable a vari# ation of the level oi the liquid by a suitable" However these apparatus, being already very bulky, would become much more so and would involve the yuse 'of .enormous volumes o liquid, Without taking into account'the fact that in these apparatus all lcalled by (Nelson, Allen-Moore,

the deposits which are formed l (precipitates,

lyte on starting the operation.v The adjustnient process gradually uncovers a part of merged part which is graduallyreduced) in everypart" of which is obtained an equal speed of etllux and in another (the part emerging on the cathodic side and gradually increasing) wherein the'eiilux speed varies continually atethe different heights. Said apparatus further', either in simple units or in aggregate units, have but :one level adjustment for all the diaphragms.y

the diaphragm dividing itLinto a zone (s uby The electrolyzers of the second type, i

fPercolation cell etc.) have always their cathodic liquid chamber empty.

The different effluxk speed at the difcil-ent Americans Qlieights compels `the constructors to limit the total height ofthe diaphragm, thus developingthe electrolyzer inthe direction only of its-length every timethey wish to increase itspower.' Thus there is a limit imposed by the concentration of the` anolyte, beyond which it is not easy to go Without recurring to an independent circulation of the anodic liquids for the'A purposeof completely ref saturatingithenr, whichV is not without inconvenience (chlorine exhalations, progressive) enrichment of theliquid in chlorates, etc.

Invthese apparatuses are not rovided lmeans to adjust the ganolyte level Wit in Wide limits'so as'to keep A,constant the working conditions ot' the electrolyzer during its operation.

The apparatus which is the objectof our invention cinn'prises a central structure suitably'arrangediandl combined on two ot itsfaces byv tWddiaphragms of a suitable material having a very limited porosity to Vreduce to the least possible .quantity the phenomenon of the diffusion of the anodic and cathodic liquids.

. liquid in This limited porosity, which is the true essential element of a high eiiiciency in this kind of apparatus, for the ltering of the a suitable' measure, requires a pronounced difference of level between the anolyte and the catholyte said diiference being obtained by suitably lifting the anodic chamber -above the upper limit of` thepdiaphragms.

By means of a suitable feeding device (not l'shown in the drawing) the level of the brine in .the anodic section may be varied during thel operation in order'to be able to vary at will the eilux speed ot' the liquid through the diaphragmnot only in relation to the working conditions but also when the permeability for maintaining said eiilux speed constant of the diaphragm changes, which generally. diminishes when the diaphragm gets old.

The cathodic chambers are kept constant* ly full up to the upper limitof the di# A aphragms, thereby obtaining the constant submerged on eiliux speed with ltering diaphragms not completely the cathodic side.l

The catholyte is continuously withdrawn from the cathodic chambers through articulated'siphons which can be` controlled separately, andv which allow to secure, with the exact'rdetermination of each level, an equal speed of eiilux on both diaphragms even when they have not the samepcrfect struc- -allows alsoto wholly `the cathodic chambers, in order to increase ture, as it happens in practice.

The articulation of the discharge siphons or partially empty v the'level difference between the anolyte and the catholyte.; in this way it will be possible towork with diaphragme, the porosity of which has been greatly reduced by use, that is to say it will be possible to lengthen the' duration ofA the diaphragm.

The annexed drawing shows by way of example in a diagrammatic section an embodiment of the electrolyzer according to our invention. 1

Thefikframes of unattachable niaterial bears"'tl1e electrodes '-b-' of anodic graphiteand-forms in the upper part a gas'v chamber e0- high enough to allow a variation of the anolyte levelwithin wide limits.

The4 cathodic s in every part of them, diier' ently from what occurs inthe cells provided chambers having solid f the perforated' tion of said spaces being connected with siphons -,ZZ.-: by means of articulated .separating the said anodic chamber from the cathodic chambers provided at their upper ends with hydrogen outlets, a feeding device for admitting -the electrolyte to -the anodic chamber, meanslfor discharging the liquid arriving in tlteigcathodic chainbers, and means for regulating the speed of the liquid passing through the said dia phragms, irrespective of the changeset` the vporosity of the said diaphragms,

2. A circulation electrolyzer as specified in claim 1,-in which the anodic chamber ex tends above tfe upper limit of the Said diaphragms, the said feeding device allowing to regulate the level of the liquid fed to the said anodic chamber, and which comprises means for regulating the level Vot' y the liquid in the cathodic chambers, for the purpose of regulating the lowof the liquid 'I through the said diaphra ms by conveniently arranging the levels 1n the anodic and 'in the cathodic chambers.4

` 3. A circulation electrolyzver as specifiedin claim 1, comprising means for regulating the level of the liquid 'inthe cathodic chamers, lated siphons through which .the catholyte is discharged. g y

4. A circulationl electrolyz'er: as specifiedin claim 1, comprisin articulated siphons in combination with t e cathodic chambers, 105

and means for adjusting'the said siphons independently of each other.

In testimony whereof we have affixed our .signatures this 21st day of September,-1922.

'FRANCESCO GIORDANI. UMBERTO lPOMrLIO.

atl

the said .means consisting in articu- 100 

